Feature request: share heads among different hydras #57

zhaojiangbin · 2015-02-26T16:56:12Z

I have different hydras using exactly same subset of heads. For example, for moving the point, both the vi-style navigation hydra and the rectangle operation hydra define h i j k heads to call same commands, respectively. Would it be possible to share these heads between the hydras?

An option is to define the common heads in a hydra and call it in bodies of vi-navigation and rect-ops. But that would require an extra pair of keys to enter and exit the sub-hydra.

I am thinking something like:

;; It could be implemented as a different function/macro if that would make more sense.
(defhydra common-heads ()
  ""
  ("h" backward-char)
  ...
  ("k" previous-line))

(defhydra vi-navigation ()
  ""
  (hydra-import common-heads :hint t) ;; shown in hint
  ("a" beginning-of-line)
  ;; other heads
  ...)

(defhydra rect-operations ()
  ""
  (hydra-import common-heads :hint nil) ;; hidden
  ;; other heads
  ...)

The function/macro hydra-import (I am making up the name here) would somehow make the heads h j k l available directly in the calling hydras. The property :hint tells whether these heads should show up in the calling hydras. Having the :exit and :foreign-keys properties would be useful, too.

I have to admit that this is only a nice-to-have minor feature. It might not even get much use. I am just tossing some ideas.

The text was updated successfully, but these errors were encountered:

abo-abo · 2015-02-26T17:10:44Z

It's a good idea, but it might be too soon to do it. Myself, I have around 10 hydras total, with
little repetition. And once something gets re-used, a need for introspection arises: common-hydras
will need a variable, a docstring and location info, and metadata. All of this it doesn't have since
it's just a macro expansion.

This might get implemented in the future, but not very soon.

zhaojiangbin · 2015-04-15T18:00:17Z

Awesome. Thanks.

occisn · 2021-03-15T17:37:36Z

@zhaojiangbin , a work-around could be to use a macro which would create specific hydras on top of a common basis.

(defmacro create-hydra-on-top-of-common-hydra (hydra-name description-string &rest keybindings)
  "Creates hydra on top of common hydra"
  `(defhydra ,hydra-name (:exit t :hint nil)
     ,(concat description-string "
Common:
-------
_h_: backward char
")
     ,@keybindings
     ("h" #'backward-char)))

(create-hydra-on-top-of-common-hydra vi-navigation-hydra
				     "
^Vi navigation:
^--------------
_a_: beginning of line
"
				     ("a" #'beginning-of-line)
				     )

(global-set-key (kbd "C-c i") #'vi-navigation-hydra/body)

Stroking C-c i then leads to:

abo-abo closed this as completed in d3d435d Apr 13, 2015

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Feature request: share heads among different hydras #57

Feature request: share heads among different hydras #57

Feature request: share heads among different hydras #57

Feature request: share heads among different hydras #57

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